Pressure responsive device



Oct. 7, 194Lv L. A, TAYLOR PRESSURE RESPONSIVE DEV ICE Filed April 28', 193

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Patented Oct. 7, 1941 PRESSURE RESPONSIVE DEVICE Laurens A. Taylor, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application April 28, 1939, Serial No. 270,60

12 Claims.

This invention relates to pressure responsive devices, and more particularly to such devices flexible diaphragms arranged therein, which are adapted to be acted upon by a fluid of variable pressure. Movement of the unit or diaphragm is transmitted by a suitable linkage to the indicating means, such as an electric circuit controller. It is an object of'this invention to provide a new and improved pressure responsive device which contains a relatively few number of parts,

is efficient in operation, rugged in construction, and'low in manufacturing costs.

It is a further object of this invention to provide a new and improved difierential pressure responsive device having pressure actuable diaphragms that are sensitive to slight changes in pressure and yet capablefof withstanding ex.- treme operating conditions without injury.

It is a further object of this invention to provide a new and improved diaphragm arrangement for fluid pressure responsive devices.

It is a still further object of this invention to provide a new and novel method of manufacturing diaphragms for fluid pressure operated devices.

In accordance with the illustrated embodiment of the invention, the fluid pressure responsive device comprises a housing having a plunger slidably arranged in aligned bores provided in two spaced apart walls thereof. Diaphragms of plastic material are molded over the ends of the plunger to the inner wall of the chambers provided' about the plunger ends in the outer side walls of the housing. The fluid under pressure acting upon the diaphragms positions the plunger and actuates a switch connected thereto in accordance with the differential condition of fluid pressure.

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto taken in connection with the accompanying drawing.

In the drawing, Fig. 1 is a cross-sectional view of a pressure responsive device constructed in accordance with one form of my invention; Fig. 2 is a plan view of the device illustrated in Fig. l with the cover removed; and Fig. 3 is a fragmentary sectional view of a portion of the device illustrating a step in the manufacture thereof.

in a fluid tight manner. may consist of any suitable material and may be secured in position in any suitable manner, it is Referring to the drawing, the pressure responsive device comprises a casing or housing 10 which may be cast or machined from any suitable metal. A recess H is provided in the lower portion of the housing defining a pair of spaced apart and substantially parallel walls l2 and I3. Aligned bores M and l5 are provided through the housing walls l2 and I3 and substantially at right angles thereto which bores may be formed by a single drilling operation. The outer ends of the bores l4 and I5 are counterbored to provide cylindrical chambers or recesses l6 and I1 concentric with the bores. A cylindrical plunger I9 is slidably arranged within the bores 14 and IS, the opposite ends thereof being preferably rounded to a substantially hemispherical curvature and extend slight distances into the chambers l6 and I! respectively. Diaphragms 20 and 2| extending over the ends of theplunger are secured to the inner end walls of the chambers While the diaphragms preferred thatthese be molded in place in a manner to be more fully described hereinafter. The outer ends of the chambers l6 and I! are closed bymeans of the plugs 22 and 23 respectively, threaded into the housing, sealing gaskets 24 and 25 being provided between the plugs and suitable shoulders in the side walls of the chambers for precluding leakage of pressure fluid therefrom. Fluid under pressure may be conducted to the chambers 16 and I! through the passages 26, 21 respectively.

A sleeve 28 is provided around the plunger 19 and is secured thereto as by means of the pin 29 extending through a cooperating hole provided in the head 30 of the sleeve and a matching hole through the plunger IS. The plunger is normally biased to an inoperative position, or to the left as shown in the drawing, by means of a spring 3| surrounding the sleeve and arranged between the wall l3 and an adjustable nut 32 threaded onto the sleeve. By varying the compression of the spring 3| by the adjustment of nut 32, the operating characteristics of the device may be adjusted as desired. Movement of .the plunger to the right is limited by the engagement of the end 33 of the sleeve 28 with the wall [3.

The movement of the plunger 19 in response to a predetermined increase of fluid pressure in the chamber l6 over that occurring in the chamher I! is adapted to be transmitted to a switch structure mounted within the upper portion of the housing. As indicated, a wall extends upwardly from the upper edge of the housing providing a compartment 36 within which the switch structure may be arranged. A crank comprising arms 31 and 38 is pivotally mounted as at 39 to a bracket 40 secured to the housing by screws 4 I. The crank is biased in clockwise direction by a small leaf spring 42 bearing against the upper surface of arm 38 whereby the arm 31 is normally maintained in engagement with the head 30 of the sleeve 23. The end of the arm 38 is provided with a pin 43 of insulating material which extends through an opening 44 in the lower contact supporting arm 45 and is adapted to engage with the resilient upper contact supporting arm 46. The left end of the lower arm 45 is secured to the terminal 41 mounted on the insulating support 48. The right end of arm 45 bearing the contact 49 is supported by means of the adjustable screw 50 threaded into the L bushing 5| mbedded in the insulating support 48. The left end of the upper contact bearing arm 46 is fixedly secured to the terminal 52, while the right end, being free from the support, carries the movable contact 53. The insulating support 48 is provided with a suitable barrier 54, also of insulating material, which extends between the terminals 41 and 52. The support 48 is secured to the housings by means of suitably arranged screws 55. Conductors to be connected to the terminals 4! and 52 may be led through the conduit indicated at 56 which is threaded into the casing wall. A cover plate 51 may be secured by means of the screws 58 onto the upper edge of the wall 35 so as to substantially enclose the mechanism and protect the same.

The operation of the device will appear obvious to those skilled in the art. In the inoperative condition of the device, the plunger I9 is biased to the left by the spring 3|. Due to the force of the spring 42, the crank arm 38 is held in its lowermost position, and the upper end of the pin 43 out of engagement with the contact arm 46. The contacts 49 and 53 are thus maintained in the circuit closing condition by virtue of the biasing force of the resilient arm 46. Upon a predetermined increase of fluid pressure in the chamber l6 over that occurring in the chamber H, as determined by the adjustment of spring 3|, the plunger I9 will be actuated to the right rotating the bell crank 38 in counterclockwise direction. The spring contact arm 46 is thereby deflected upwardly to separate the contacts 49 and 53. Upon a predetermined equalization of the pressures obtaining in the chambers l6 and H, the plunger IE will be restored to its normal condition allowing the reclosure of the contacts 49 and 53.

In accordance with my invention, the resilient diaphragms 20 and 2| are preferably molded directly into the housing during the assembly of the mechanism. While any suitable plastic molding compound may be used, I prefer to use a synthetic rubberlike material which is characterized by its ability to resist deterioration when used with oil as an operating fluid for the device. The plunger is first arranged within the housing bore with the sleeve, the spring, and the adjusting nut assembled thereabout, the sleeve being secured to the plunger by the pin 29. A shim 50, as indicated in Fig. 3, is inserted between the head 39 of the sleeve 28 and the adjacent housing wall 12 positioning the plunger slightly to the right of its normal or inoperative position to a point which would cause separation of the switch contact. A measured portion of the molding compound, usually in powdered form, is poured into the chamber IT, a suitable bonding agent or cement first having been applied to the inner end and adjacent side walls of the chamber. Care is taken not to apply any cement to the portion of the plunger extending into the chamber, since it is not to be bonded with the diaphragm and must be left tree so that it will slide freely within the housing in response to changes in the condition of the fluid pressure. The molding compound is then suitably compressed in the end of the chamber by means of a plug 6! screwed into the threaded end of the counterbore. The end 63 of the plug is suitably machined to give the desired surface to the diaphragm. The diaphragm itself is of substantially uniform thickness over the end of the plunger and relatively thicker at that portion which is bonded to the housing. It will be noted that the inner end walls of the chambers are provided with annular V-shaped grooves 34 for increasing the end wall surface whereby a stronger bond or seal is effected between the diaphragm and the housing. In a manner as described above, the inner end and side walls of the opposite chamber 1 6 are coated with a bonding agent or cement and a portion of the molding compound is poured therein after which the plug 62 is inserted to compress the compound therein. It will be noted that the plunger is substantially secured against movement by the other plug 5| acting against the right end of the plunger. Before the remaining parts of the mechanism are assembled, the housing is then heated to the proper molding temperature for transforming the compound from the powder form into the resilient diaphragm as indicated. After the housing has cooled, the molding plugs BI and 52 may be removed, the plugs 22 and 23 substituted therefor, the shim 50 removed, and the remaining parts of the device assembled. Upon the removal of the shim 60, the spring 3| will force the plunger 19 to the left a distance equal to the thickness of the shim correspondingly distending the diaphragm 20 and moving the opposite end of the plunger slightly away from the diaphragm 2|. This is the normally inoperative condition of the device, the purpose being to remove the effect of the initial resistance of the diaphragm to fiexion upon the operating force required for actuating the plunger IS. The operating characteristics of the device can thereby be more accurately determined by the adjustment of the compression of spring 3|.

The pressure operating mechanism is extremely simple in design, yet very rugged. The sides of the diaphragms opposite to those acted upon by the fluid pressure are supported over their entire area and since the movement of the plunger in both directions is positively limited, an excessive increase in pressure in either of the chambers l6 and I! will not result in a failure of the diaphragms. The diaphragms thus being substantially indestructible, the operating life of the device is thereby materially lengthened.

While in the modification shown the pressure responsive mechanism is adapted for operatin a switch of the single-pole, single-throw type, it is obvious that by simple modifications made by one skilled in the art it may be adapted for actuating a switch of any other desired type. Furthermore, instead of a switch, the pressure responsive device may be utilized for actuating any other suitable indicating means.

Having described the principle of operation of my invention together with the apparatus which invention may be carried out by other means.

- What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electrical controller, a pressure operated mechanism comprising a housing, a cylindr-ical bore through said housing, a plunger fitted and slidably arranged in said bore, a chamber in said housing concentric with one end of said bore,

means for biasing said plunger so that the end thereof projects into said chamber a predeterbonded thereto, and means for admitting fluid under pressure to said chamber whereby said diaphragm is forced against said plunger to actuate said plunger in accordance with the fluid pressure.

2. In an electrical controller, a pressure operated mechanism comprising a housing, a recess in said housing defining a pair of spaced apart and substantially parallel walls, a bore extending through said housing walls and substantially perpendicular thereto, one outer end of said bore being counterbored to provide a chamber concentric with said bore, a plunger fitted and slidably arranged in said bore, said plunger having a rounded end projecting into said chamber, a diaphragm of relatively flexible material molded in said chamber and sealed to the end wall thereof, said diaphragm covering and fitting closely over said rounded end of said plunger, means for biasing said plunger against said diaphragm, and means for conducting fluid under pressure to said chamber whereby said plunger is actuated against said biasing means in accordance with the pressure exerted upon said diaphragm by said fluid.

3. In an electrical controller, a pressure operated mechanism comprising a housing, a recess in said housing defining a pair of spaced apart and substantially parallel walls, a bore extending through said housing walls and substantially at right angles with respect thereto, a cylindrical plunger slidably arranged in said bore, the outer ends of said bore being enlarged to provide concentric chambers surrounding the ends of said plunger, the ends of said plunger extending into said chambers being substantially hemispherically rounded, diaphragms of relatively flexible material molded in said chambers and sealed only to the inner end walls thereof and covering said rounded ends of said plunger, means for admitting fluid under pressure to said chambers for actuating said plunger in accordance with the differential of the pressures acting upon said diaphragms.

4. In an electrical controller, a pressure operated mechanism comprising a housing, a recess in said housing defining a pair of spaced apart and substantially parallel walls, a bore through said housing and said walls substantially at right angles to said walls, the opposite ends of said bore being counterbored to provide enlarged chambers concentric with said bore, a plunger fitted and slidably arranged in said bore, the opposite ends of said plunger extending slightly into said chambers, diaphragms of relatively flexible material molded to the bottom of said chambers and loosely covering the ends of said plunger, said diaphragms being adapted to be forced against said plunger whereby said plunger is actuated in accordance with the differential of pressure acting upon said diaphragms, means for closing the outer ends of said chambers, and passages extending through said housing for conducting fluid under pressure to said chambers.

5. In an electrical controller, a pressure operated mechanism comprising a housing defining a pair of spaced apart and substantially parallel Walls, a bore extending through said housing walls and substantially at right angles with respect thereto, a plunger arranged in said bore, recesses in said housing surrounding the ends of said plunger, relatively flexible diaphragms secured in said recesses fitting over the ends of said plunger, means foradmitting fluid under pressure to said recesses for actuating said plunger in accordance with the differential pressure acting on said diaphragms, a sleeve arranged around said plunger between said spaced apart walls and secured to said plunger, said sleeve acting as a stop for said plunger in both directions of movement, a spring arranged around said plunger between one of said walls and an adjustable nut on said sleeve for biasing said plunger to one limit of movement.

6. In an electrical controller, a pressure operated mechanism comprising a housing having a pair of spaced apart and. substantially parallel walls, a bore extending through said walls and substantially at right angles thereto, a plunger slidably arranged in said bore, recesses in the outer surfaces of said housing concentric with said bore, the ends of said plunger normally extending into said recesses a predetermined distance, diaphragms of relatively flexible material sealed to the inner end walls of said recesses adjacent said bore and normally in engagement with said plunger over the portions thereof extending into said recesses, means for admitting fluid to said recesses, a sleeve arranged around said plunger between said spaced apart walls and secured to said plunger, said sleeve adapted to engage at opposite ends with said walls for limiting the movement of said plunger in opposite directions, a shoulder on said sleeve, a member pivoted to said casing having a first portion biased into engagement with said shoulder and a second portion operatively associated with an electrical switch.

7. In a fluid pressure operated device, a casing, a chamber in said casing, a cylindrical bore through one wall of said chamber, a cylindrical plunger slidably arranged in said bore, said plunger having a rounded end projecting into said chamber, means for normally biasing said plunger to a predetermined position in said bore, a resilient diaphragm of plastic material molded in said chamber against said one wall and against said rounded end of said plunger, said diaphragm being bonded to said one wall and not to said plunger, said diaphragm being molded in said chamber with said plunger slightly displaced from said normally biased position.

8. In a fluid pressure operated device, a casing, a chamber in said casing, a cylindrical bore through one wall of said chamber, a cylindrical plunger slidably arranged in said bore and having a rounded end projecting into said chamber, means for normally biasing said plunger to a predetermined position in said bore, a diaphragm of resilient plastic material molded in said chamber against said one wall and against said rounded end of said plunger without being bonded to the latter, said plunger being held in a predetermined position in said bore during the molding of said diaphragm.

9. In a fluid pressure operated device, a casing, a chamber in one Wall of said casing, a bore extending through one wall of said chamber, a plunger slidably arranged in said bore, a resilient diaphragm of moldable plastic material secured to said one wall around said bore, said diaphragm loosely fitting around the end of said plunger projecting through said bore into said chamber.

10. The method of manufacturing a resilient diaphragm for a pressure responsive device having a fluid pressure chamber and a plunger slidably arranged therein which method comprises securing said plunger in a position slightly displaced from its normal inoperative position, molding a diaphragm in said chamber over the end of said plunger projecting into said chamber from a moldable plastic material and bonding said diaphragm only to said chamber around said plunger.

11. The method of manufacturing a resilient diaphragm for a fluid pressure responsive device having a fluid pressure chamber and a plunger slidably arranged therein which method comprises molding a diaphragm in said chamber over the end of said plunger from a moldable plastic material, and bonding said diaphragm only to said chamber around said end of said plunger.

12. Differential pressure responsive device comprising a casing having walls integral with a bottom, opposite portions of the bottom forming two lined cylindrical chambers, a recess being formed in the bottom between the chambers, two aligned bores connecting the recess to the chambers, a plunger slidably projecting through the bores into the cylindrical chambers, resilient diaphragms of rubber-like material molded to the cylindrical chambers and loosely engaging the ends of the plunger, and means projecting into the recess and engaging the plunger to be actuated in response to changes in pressure difference between the two chambers.

LAURENS A. TAYLOR. 

